Caracterização química e atividade antileishmania das cascas de Aspidosperma Excelsum Benth (Apocynaceae)

Abstract

Neglected Tropical Diseases (NTDs) affect more than 1 billion people, primarily in vulnerable populations, causing significant social and economic impacts. Leishmaniasis stands out among these diseases due to therapeutic limitations such as toxicity, high cost, and increasing resistance. In this context, Amazonian biodiversity emerges as a promising source of bioactive compounds. The genus Aspidosperma, traditionally used in the treatment of infectious diseases, is rich in indole alkaloids with antimicrobial and antileishmanial properties. This study chemically characterized the bark extracts of Aspidosperma excelsum Benth. and evaluated their antioxidant and antileishmanial activities against Leishmania (Viannia) guyanensis. ESI-MS analysis identified various indole alkaloids, such as reserpiline, yohimbine, ajmalicine, 11-methoxy-yohimbine, yohimbinic acid, corinantheidol, and quinic acid, distributed distinctly among the extracts. The AEME extract showed the highest antioxidant activity in all assays (DPPH•, ABTS•+, FRAP), while AEAC stood out in the ABTS•+ and FRAP tests. Regarding antileishmanial activity, AEAC presented IC50 values of 26.8 μg/mL (24 h) and 24.6 μg/mL (48 h), being the most promising, followed by AEME. In silico evaluation showed that small structural modifications influence interactions with the enzyme NMT (N-Myristoyltransferase). Among the six metabolites analyzed, ajmalicine and yohimbinic acid exhibited the most favorable interactions with key residues of the active site. These findings suggest that A. excelsum is a relevant source of natural antioxidants and antileishmanial compounds, paving the way for future studies on isolation, characterization, and efficacy evaluation in advanced experimental models.